1. Technical Field
The present invention relates to field emission displays, particularly, to a carbon nanotube based field emission display.
2. Discussion of Related Art
Conventional field electron emission displays include field emission displays (FED) and surface-conduction electron-emitter displays (SED). Field electron emission displays can emit electrons in the principle of a quantum tunnel effect opposite to a thermal excitation effect, which is of great interest from the viewpoints of promoting high brightness and low power consumption.
Referring to FIG. 3, according to the prior art, a field emission display 300 generally includes a transparent substrate 310, an insulating substrate 330, and a number of electron emission units 320, a number of cathode electrodes 328, a number of gate electrodes 324, and a number of spacers 340. The transparent substrate 310 is spaced from the insulating substrate 330 by a number of spacers 340. A conductive layer 316, a phosphor layer 314, and a filter layer 312 are located on the surface of the transparent plate 310 facing the insulating substrate 330. The electron emission units 320, cathode electrodes 328, and gate electrodes 324 are located on the insulating substrate 330. The cathode electrodes 328 and the gate electrodes 324 cross each other to form a plurality of crossover regions. A plurality of insulating layers 326 is arranged corresponding to the crossover regions. Each electron emission unit 320 includes at least one electron emitter 322. The electron emitter 322 is in electrical contact with the cathode electrode 328 and spaced from the gate electrode 324. When receiving a voltage that exceeds a threshold value, the electron emitter 322 emits electron beams towards the gate electrodes 324. When a higher voltage is added on the conductive layer 316 and the cathode electrodes 328, the electron beams emitted from the electron emitters 322 are attracted to the phosphor layer 314. The luminance is adjusted by altering the applied voltage. However, the distance between the gate electrode 324 and the cathode electrode 328 is difficult to control well. As a result, the driving voltage is relatively high, thereby increasing the overall operational cost.
Referring to FIG. 4 and FIG. 5, according to the prior art, a surface-conduction electron-emitter display 100 includes an insulating substrate 130, a number of spacers 140, a transparent substrate 110 spaced from the insulating substrate 130 by a number of spacers 140, and a number of electron emission units 120, a number of row electrodes 134, a number of column electrodes 132 located on the insulating substrate 130. An anode conductive layer 116, a phosphor layer 114, and a filter layer 112 are located on the surface of the transparent plate 110 facing the insulating substrate 130. The row electrodes 134 and column electrodes 132 are parallel to and spaced from each other. Every two adjacent row electrodes 134 and every two adjacent column electrodes 132 form a square 138. The electron-emission units 120 are located on the insulating substrate 130. Each of the electron-emission units 120 is corresponding to one square 138. The electron-emission unit 120 includes, a cathode electrode 125, a gate electrode 126, and an emitter 127 located on the cathode electrode 125 and the gate electrode 126. An electron-emission gap 124 is formed in the middle of the electron emitter 127. The cathode electrode 125 and gate electrode 126 are spaced from each other. The cathode electrode 125 is electrically connected to the corresponding column electrodes 132 and the gate electrode 126 is electrically connected to the corresponding row electrodes 134. When a voltage is applied between the cathode electrode 125 and the gate electrode 126, an electron current is formed across the electron-emission gap 124. When a higher voltage is applied on the anode conductive layer 116, a portion of the electrons of the electron current in the electron-emission gap 124 is attracted to the phosphor layer 114. The luminance is adjusted by altering the applied voltage. However, because the electron current includes the emission current and conduction current, and only few electrons can escape to the phosphor layer 114, and the efficiency of the surface-conduction electron-emitter display 100 is relatively lower than 3%.
What is needed, therefore, is to provide a highly efficient field emission display with a simple structure.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one embodiment of the present field emission displays, in at least one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.